Surgical Needle Coatings and Methods

ABSTRACT

The present invention provides novel medical devices for use in surgical procedures and methods for manufacturing novel medical devices. In some embodiments, the novel medical devices can include surgical needles that are capable of being repeatedly passed through tissue using minimal force. More particularly, the surgical needles can be manufactured with one or more coatings that provide the surgical needles with both durability and lubricity for ease of repeated and successive passes through tissue. Novel methods for manufacturing the surgical needles and for providing and applying coatings to the surgical needles are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/042,752, entitled “Surgical Needle Coatings and Methods,” filed onFeb. 12, 2016, which is a continuation of U.S. application Ser. No.12/858,481, filed on Aug. 18, 2010, now U.S. Pat. No. 9,259,219, whichis a continuation-in-part of U.S. application Ser. No. 12/614,669, filedon Nov. 9, 2009, and U.S. application Ser. No. 12/614,665, filed on Nov.9, 2009, each of which is incorporated by reference herein in itsentirety.

FIELD OF THE INVENTION

The present invention relates to coated medical devices and methods formanufacturing the same.

BACKGROUND OF THE INVENTION

Coated medical devices which repeatedly come into contact with bodilytissue, such as surgical needles, are required to be lubricious, yetdurable enough to withstand multiple contacts with tissue. However,lubricity is often sacrificed at the expense of making a more durablecoating that adheres well to medical devices. There are many coatingmaterials that are extremely lubricious, but either do not adhere wellto the desired substrates or easily wear off the substrate during use.Likewise, many extremely durable coatings exist, but these coatings arenot considered lubricious. Various attempts have been made to findcoating compositions and/or a method of applying coating compositionsthat can provide durability and lubricity simultaneously. Accordingly,the present invention solves this problem by providing coatingcompositions and methods of application, which provide both durabilityand lubricity, as well as decreased manufacturing time.

SUMMARY OF THE INVENTION

The present invention provides methods and devices for providing adurable and lubricious body, structure, and/or medical device. In oneexemplary embodiment, a method for coating a body, structure, and/ormedical device is provided and can include providing a medical deviceand applying a single, homogenous coating to at least a portion of asurface of the medical device with a thickness in the range of about 1micron to about 12 microns. While the single, homogeneous coating canhave many components, in some embodiments, the single, homogeneouscoating can include a vinyl functionalized organopolysiloxane and apolydimethylsiloxane. Applying a single, homogeneous coating to asurface of the medical device can include applying a coating with athickness in the range of about 1 micron to about 3.5 microns. In oneembodiment, the surface of the medical device can include a primer thatincludes a silicone. The single, homogeneous coating can be sprayed ontoa surface of the medical device. The surface can be an exterior surface,an interior surface, or some combination of exterior and interiorsurfaces. In some embodiments, the single, homogeneous coating can becured on the surface of the medical device for a time in the range ofabout 10 seconds to about 30 seconds.

The medical device can be formed of any suitable material known in theart, including tungsten alloys, refractory alloys, stainless steels,nitinol, and tantalum. The tungsten alloy can be, for example,tungsten-rhenium. In some embodiments, applying a single, homogeneouscoating can include delivering the single, homogeneous coating to thesurface of the medical device in a high vapor pressure, low boilingpoint solvent. The high vapor pressure, low boiling point solvent canbe, for example, a hydrofluoroether solvent. The single, homogeneouscoating can be applied to any medical device known in the art, and insome embodiments, the method can include providing an elongate medicaldevice having a tissue penetrating portion.

In other aspects, devices are provided, and in one exemplary embodiment,a coated device is provided and can include a substrate, wherein atleast a portion of the substrate is coated with a coating comprising avinyl functionalized organopolysiloxane and a polydimethylsiloxane. Thecoating can be a single layer having a thickness in the range of about 1micron to about 3.5 microns. In some embodiments, the coating can beconfigured to be delivered to the substrate in a high vapor pressure,low boiling point solvent such that the body exhibits substantiallyconstant penetration over thirty passes of the body through tissue. Thedevice can be formed from any suitable material known in the art,including tungsten alloys, refractory alloys, stainless steels, nitinol,and tantalum. In some embodiments, the substrate can be a medicaldevice. Further, the coating includes vinyl functionalizedorganopolysiloxane in the range of about 10 wt. % to about 90 wt. % andpolydimethylsiloxane in the range of about 10 wt. % to about 90 wt. %.The vinyl functionalized organopolysiloxane can be for example,Momentive® Product Code No. MSC2631 silicone manufactured by Momentive®Performance Materials of Waterford, N.Y.

In another aspect, a medical device is provided and can include astructure and/or body and a single, homogeneous coating comprising alubricious silicone disposed on a surface, e.g., an exterior and/orinterior surface of the body. The body can exhibit, for example,substantially constant penetration over thirty passes of the bodythrough tissue. In some embodiments, the single, homogeneous coating canbe formed of a vinyl functionalized organopolysiloxane and apolydimethylsiloxane. The body can have many configurations known in theart, and can include an elongate body having a tissue penetratingportion. In addition, the medical device can be an assembly including aplurality of components and/or operating parts, and the body can be oneof the plurality of components and/or operating parts. One or more, andin some cases all, of the plurality of components and/or operating partscan be coated with the single, homogenous coating.

In some embodiments, the single, homogeneous coating can be configuredto be cured at a temperature of about 200 degrees Celsius using infraredradiation having a wavelength in a range of about 1.4 μm to about 3.0The single, homogeneous coating can also be configured to be cured for atime in the range of about 1 second to about 60 seconds and/or for atime in the range of about 10 seconds to about 30 seconds. In otherembodiments, the single, homogeneous coating can be configured to becured on the surface of the body in a convection oven for a time in therange of about 1 hour to about 5 hours at a temperature of about 60degrees Celsius to about 180 degrees Celsius and/or for a time in therange of about 2.5 hours to about 3.5 hours at a temperature of about100 degrees Celsius to about 140 degrees Celsius.

In still further aspects, methods for coating a medical device areprovided and can include providing a lubricious silicone coatingcomprising a solvent having a boiling point less than about 43 degreesCelsius. The method can also include applying the lubricious siliconecoating to the medical device and curing the lubricious silicone coatingfor a time in the range of about 1 second to about 60 seconds. Thesolvent can have a vapor pressure of, for example, about 350 mm Hg.Further, curing the lubricious silicone coating can include curing thecoating at a temperature of about 200 degrees Celsius for a time in therange of about 10 seconds to about 30 seconds using infrared radiationhaving a wavelength in the range of about 1.4 μm to about 3.0 μm. Whilethe lubricious silicone coating can be formed of many compositions, inone embodiment, the lubricious silicone coating can include a single,homogeneous layer of a vinyl functionalized organopolysiloxane and apolydimethylsiloxane.

The invention will be more fully understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one exemplary embodiment of a surgicalneedle;

FIG. 2 is a side view of a carrier strip with surgical needles attachedthereto for transporting the surgical needles;

FIG. 3A is a perspective view of one exemplary embodiment of a swirlcoating machine for swirl coating surgical needles;

FIG. 3B is a perspective view of another exemplary embodiment of a swirlcoating machine for coating suspended surgical needles;

FIG. 4A is a flowchart of one exemplary method for manufacturing andcoating surgical needles using two coatings;

FIG. 4B is a flowchart of one exemplary method for manufacturing andcoating surgical needles using a single, homogeneous coating;

FIG. 5 is a graphical representation comparing the force required topass primed and unprimed surgical needles through synthetic media;

FIG. 6 is graphical representation comparing the force required to passsurgical needles that are swirl coated through synthetic media versussurgical needles that are dip coated;

FIG. 7 is a graphical representation comparing forces associated withtwo different coating compositions and application methods;

FIG. 8 is a graphical representation comparing the force required topass surgical needles that are swirl coated through synthetic mediaversus surgical needles that are dip coated;

FIG. 9 is a graphical representation comparing the forces associatedwith passing three different coating compositions and applicationmethods through human cadaver tissue; and

FIG. 10 is a graphical representation comparing the forces associatedwith passing needles coating with a single, homogeneous coating andneedles coated with two coatings through synthetic media.

DETAILED DESCRIPTION OF THE INVENTION

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the devices and methods disclosed herein. One ormore examples of these embodiments are illustrated in the accompanyingdrawings. Those skilled in the art will understand that the devices andmethods specifically described herein and illustrated in theaccompanying drawings are non-limiting exemplary embodiments and thatthe scope of the present invention is defined solely by the claims. Thefeatures illustrated or described in connection with one exemplaryembodiment may be combined with the features of other embodiments. Suchmodifications and variations are intended to be included within thescope of the present invention.

The present invention generally provides novel medical devices for usein surgical procedures and methods for manufacturing novel medicaldevices. In some embodiments, the novel medical devices can include oneor more bodies, one or more structures, and/or an assembly of componentsand/or operating parts. In one embodiment, the novel medical devices caninclude novel surgical needles that are capable of being repeatedlypassed through tissue with ease of penetration. More particularly, thenovel surgical needles can be manufactured with two or more differentcoats and/or coatings that provide the surgical needles with bothdurability and lubricity for ease of repeated and successive passesthrough tissue. Novel methods for manufacturing the surgical needles andfor providing and applying durable coatings to the surgical needles arealso provided. As they are used herein, the terms “coat” and “coating”are used interchangeably.

While many types of medical devices and surgical needles arecontemplated, in one embodiment, a biocompatible surgical needle isprovided having a single, homogeneous coating applied thereto such thatthe coating is both durable and lubricious. The single, homogeneouscoating can be applied to an exterior and/or interior surface of amedical device, and can be applied to one or more portions of theexterior and/or interior surfaces. The single, homogenous coating can bea partial and/or discontinuous coating of the exterior and/or interiorsurface, or it can be applied to the entire exterior and/or interiorsurface. In another embodiment, two or more different coatings can beapplied successively to the surgical needle. A base coating can beapplied to the needle to provide durability for a different top coatingthat is applied to provide lubrication. The base coating can also belubricious to enhance the lubricity of the top coating. In someembodiments, the single, homogeneous coating can crosslink with itselfand/or the base and top coatings can interact, for example, bycrosslinking or by one or more other bonding mechanism. Because of thebonding between the base coating and top coating, the base coatingretains the top coating on the surgical needle. In this way, the basecoating can assist in preventing the top coating from wearing and/orrubbing off after repeated passes through tissue. In other embodiments,each of the base coating and/or the top coating can crosslink withitself. The interaction between components within the single,homogeneous coating and/or between the durable base coating and thelubricious top coating assists in maintaining lubrication of thesurgical needle so that it can consistently and repeatedly be passedthrough tissue with minimal force required.

Any number of coatings can be applied to the surgical needle dependingon the surgical application and the composition of the surgical needle.For example, in another embodiment a primer coating can be applied tothe surgical needle before the single, homogeneous coating and/or beforethe base and top coatings are applied. The primer coating can bedifferent from the single, homogeneous coating or from the base and topcoatings and it can bond with a surface of the surgical needle toprovide an appropriate and secure surface on which to apply the basecoating. In turn, the single, homogeneous coating and/or the basecoating can bond to the primer coating such that the primer coatingsecurely retains the single, homogeneous coating or the base coating onthe surgical needle.

Novel methods for applying the coatings to various medical devices, suchas surgical needles, are also provided. In some embodiments, a surgicalneedle can be spray coated with one or more coatings to provide thesurgical needle with a uniform distribution thereof. For example, aspray coating machine having two spray nozzles directed toward oneanother can be provided for applying the single, homogeneous coating orfor successively applying each top and base coating. One or moresurgical needles can be passed between the two spray nozzles as they arespraying a coating. Such a configuration allows for uniform distributionof the coating on the surgical needle and minimizes the risk of poolingand/or dripping of the coating. Multiple coatings can be applied usingthis method, and prior to and/or after application of each coating, thesurgical needle can be cured for a sufficient period of time effectiveto set and bond the coating(s). As will be discussed in more detailbelow, novel combinations of solvents and coating materials can allowfor substantially reduced cure times when compared with techniques knownin the art.

Exemplary surgical needles of the type contemplated herein can generallybe used for any surgical procedures now known or yet to be developed.The surgical needles can be capable of penetrating and passing throughany type of tissue, including any type of mammalian tissue includingsoft and hard tissues and tissues that have been calcified, and can beused to apply sutures to close an incision or wound, pass suture orother material through tissue, and/or simply create an opening intissue. A person skilled in the art will appreciate the variety of usesfor the surgical needles described herein.

Exemplary surgical needles can generally include an elongate member witha tissue penetrating tip on a distal end thereof for penetrating throughtissue. The tissue penetrating tip can be pointed and can be as sharp oras dull as required for a particular surgical procedure. In someembodiments, the surgical needle can also include a suture attachmentportion disposed on a proximal end of the elongate member for receivingand retaining suture. The surgical needle can have any geometry known inthe art, including straight, taper point, taper cut, cutting edge,bayonet-shaped, curved, circular, etc. In addition, the surgical needlecan have any cross-section including, but not limited to, round body,rectangular body, square body, ovular body, and I-beam. A person skilledin the art will appreciate the various combinations of shapes andcross-sections possible for a given needle.

In the manufacturing process, surgical needles can have a straightenedand/or hook-shaped grasping portion to assist in applying coatingsthereto. A conveyer mechanism and/or carrier strip for manufacturing aneedle and/or moving a needle through a coating machine and/or curingmechanism can retain the needle for manufacturing, coating, and curingby attaching to the grasping portion. An exemplary carrier strip 20 foruse with surgical needles 24 is illustrated in FIG. 2. The carrier strip20 includes various latches 22 for retaining the curved surgical needles24 thereon. This allows the surgical needles 24 to be moved using aconveyor style mechanism during the coating and/or curing process.

One exemplary embodiment of a surgical needle is illustrated in FIG. 1.As shown, a surgical needle 10 is provided having a curved elongate body16 with a tissue penetrating tip 12 formed on a distal end thereof. Thetip 12 has a circular cross-section and terminates in a sharp point forpenetrating tissue. The curved elongate body 16 extends between the tip12 and a suture attachment portion (not shown) and is in the form of anarc with a flattened, rectangular cross-section. While the surgicalneedle 10 can have any relative dimensions as needed, in the illustratedembodiment, a width W of the needle 10 is on the order of a height H ofthe needle 10. A suture attachment portion can have any form as neededfor receiving and retaining suture.

Exemplary surgical needles can be formed of any suitable, biocompatiblematerial known in the art. In some embodiments, a surgical needle can bemade of a metallic alloy, including, but not limited to, titanium,stainless steels such as 420 stainless steel, 455 stainless steel,ETHALLOY® Needle Alloy, and 302 stainless steel, refractory alloys,nitinol, tantalum, as well as various other materials and alloys knownin the art. In other embodiments, surgical needles can be made from atungsten-rhenium alloy. Use of tungsten-rhenium alloy in making surgicalneedles can give the needles greater stiffness, strength, and ductilitythan the use of some other materials. Increased stiffness and strengthproperties allow the needle to be resistant to elastic deformation andto thus resist bending and springing when pushed through tough tissue,for example, calcified tissue. Increased ductility prevents the needlefrom breaking when bent or curved by a surgeon. Any of the needle alloycompositions can contain some percentage of any one or more of nickel,cobalt, chromium, molybdenum, tungsten, rhenium, niobium, etc. Exemplaryneedles and methods for manufacturing needles and carrier strips can befound in U.S. Pat. No. 6,018,860, entitled “Process for ManufacturingDrilled Taper Point Surgical Needles,” which is hereby incorporated byreference in its entirety.

In some embodiments, two or more different coatings can be used toprovide exemplary surgical needles with a durable lubricious surface forrepeated passes through tissue. In one exemplary embodiment, a base coatcan be used to coat an external surface of a surgical needle to providedurability to a top coat that is applied onto the base coat and thatprovides lubrication. The base coat preferably bonds with the top coatand thus prevents and/or lessens wear associated with repeatedpenetrations and passes through tissue. In some embodiments, a primercoat can optionally be applied prior to the base coat. The primer coatcan bond with the surface of the surgical needle to provide a bondingsurface for the base coat. The primer coat can add additional durabilityagainst wear for the base coat and top coat.

The base coat can include, for example, a silicone based compositioncharacterized as a vinyl functionalized organopolysiloxane. The basecoat solution includes a vinyl functionalized organopolysiloxane,polymethylhydrogen siloxane fluid crosslinking agent, and optionally acatalyst such as a conventional metal catalyst such as platinum or tin.The organopolysiloxane base polymer can be, for example, Momentive®Product Code No. MSC2631 silicone manufactured by Momentive® PerformanceMaterials of Waterford, N.Y. Further information on the MSC2631composition is available from the manufacturer's MSDS.

The base coat can be prepared using any high vapor pressure, low boilingpoint solvent known in the art. In some embodiments the solvent can be ahydrofluorether (“HFE”) (e.g., HFE 72-DE solvent manufactured by 3M® ofSt. Paul, Minn.). The HFE solvent acts as a carrier for the siliconecomposition. It evaporates quickly from a composition under ambientconditions to limit migration of other substances in the composition andthus drastically reduces cure time of the composition. In addition, theHFE solvent leaves no residue after evaporation. It complies with healthand safety regulations and is environmentally friendly. As will beappreciated by those skilled in the art, any suitable solvent can beused including, but not limited to, HFE, xylene, heptane, IsoPar K (DowCorning), napthalene, toluene, and hydrofluorocarbons.

Additionally, a catalyst and a crosslinker can be added to the basecoat. For example, Momentive® Product Code No. SS8010 platinum catalyst(“catalyst”) and Momentive® Product Code No. SS4300 crosslinker(“crosslinker”), both manufactured by Momentive® Performance Materialsof Waterford, N.Y., can be added during the preparation of the base coatto act as a crosslinker and catalyst. As will be appreciated by thoseskilled in the art, any suitable catalysts and crosslinkers can be usedincluding, but not limited to, other crosslinkers containing asilicon-hydrogen moiety. Other catalysts may include conventional metalcatalysts such as tin.

In preparing an exemplary base coat, 27.57 wt. % of the base siliconepolymer, for example, a vinyl-functionalized organopolysiloxane, can becombined with 72.27 wt. % of the HFE solvent and mixed and/or agitatedfor an appropriate period of time, for example, for about five minutes.The catalyst can then be added to the mixture at 0.02 wt. % and thecrosslinker can be added at 0.14 wt. %. The mixture can be agitated foranother few minutes to ensure homogeneity, for example, about one to twomore minutes. For an exemplary 48.43 g base coat sample, 13.35 g of thebase silicone polymer can be combined with 35.00 g of the HFE solvent,0.012 g of the catalyst, and 0.068 g of the crosslinker.

A top coat can be applied to a surgical needle. In some embodiments, thetop coat can include a silicone based composition characterized as ahydroxyl terminated polydimethylsiloxane. The hydroxyl terminatedpolydimethylsiloxane generally includes dimethyl siloxane-hydroxyterminated, methylhydrogen siloxane, and trace amounts of several othersiloxanes. The hydroxyl terminated polydimethylsiloxane can be, forexample, NuSil® Technologies Silicone Product No. MED4162 manufacturedby NuSil® Technologies of Carpentaria, Calif., which is a dispersionthat contains 30% solids silicone in a 70% xylene solvent carrier.

The top coat can be prepared using a solvent, for example, the HFEsolvent or any other compatible volatile-solvent. In preparing anexemplary top coat, 26 wt. % of the top silicone polymer can be combinedwith 74 wt. % of the HFE solvent. For example, for a 50 g top coatsample, 13.00 g of the top silicone polymer can be combined with 37.00 gof the HFE solvent.

In some embodiments, a primer coat can optionally be applied to asurgical device prior to applying the base coat. The primer coat canhave any formulation capable of bonding to a surgical needle and capableof providing an appropriate substrate for applying a base coat. In oneembodiment, the primer coat can be formed of, for example,polyalkylsiloxane and tetraethyl silicate. A polyalkylsiloxane andtetraethyl silicate primer coat can be formulated for coatingdifficult-to-bond substrates such as, for example, tungsten-rheniumalloys.

One example of a polyalkylsiloxane and tetraethyl silicate primer coatis Momentive® Product No. SS4044P (“SS4044P primer”) manufactured byMomentive® Performance Materials of Waterford, N.Y. The SS4044P primercan include Momentive®) 10-30 wt. % of acetone, 1-5 wt. % of butanol,10-30 wt. % of xylene isomers mixture, 5-10 wt. % of ethylbenzene, 10-30wt. % of 2-propanol, 1-5 wt. % of tetraethyl silicate, and 10-30 wt. %of polyalkylsiloxane. Further information on the SS4044P primercomposition is available from the manufacturer's MSDS.

In general, as noted above, the primer coat can covalently bond to thesurgical needle to provide a substrate on which to apply other coatings.The base coat can be applied on top of the primer coat. As the top coatis applied over the base coat, the base coat will bond with the top coatto provide durability to the top coat. In essence, the bonding betweenthe primer coat and the surgical needle anchors the other two coats tothe needle surface. The bonding of the base coat to both the primer coatand the top coat anchors the top coat to the primer coat, and thus tothe surgical needle surface, giving the top coat extended durability.

The coatings can generally be applied at any thickness as needed. Thethickness of the individual coatings and the combined coatings should besufficient to effectively provide the desired characteristics. Forexample, the primer coat can be applied to have a thickness in the rangeof about 0.01 μm to about 1 The base coat and the top coat can beapplied with a thickness in the range of about 1 μm to about 7 In anexemplary embodiment, the top coat can have a thickness that is at leastabout 50% less than a thickness of the base coat. A person skilled inthe art will appreciate that the thicknesses of the coatings can varydepending on a particular application.

In another embodiment, a medical device such as a surgical needle can becoated with a single, homogeneous durable and lubricious coatingcomposed generally of a combination of a vinyl-functionalizedorganopolysiloxane, for example, Momentive® Product Code No. MSC2631silicone manufactured by Momentive® Performance Materials of Waterford,N.Y., and a hydroxyl terminated polydimethylsiloxane, for example,NuSil® Technologies Silicone Product No. MED4162 manufactured by NuSil®Technologies of Carpentaria, Calif., which may also include acrosslinker or catalyst. The single, homogeneous coating can be ahomogeneous mixture of the vinyl-functionalized organopolysiloxane andthe hydroxyl terminated polydimethylsiloxane such that when it isapplied to a surface of a surgical needle, there is a single homogeneouslayer formed thereon. For example, in some embodiments, the single,homogeneous coating can be a mixture of the top and base coatings notedabove. In other embodiments, it can be any combination of the durableand lubricious materials noted herein. The single, homogeneous coatingcan be applied to the medical device in a single application step, andin some embodiments, the single, homogeneous coating can be formed ofvarious ratios of the top and base coatings described above. The single,homogeneous coating can be applied directly to the surface of a medicaldevice and can be the only coating applied to the medical device suchthat there is a single coating layer formed on the surface thereof.

In preparing an exemplary single, homogeneous coating composition, thevinyl-functionalized organopolysiloxane and the hydroxyl terminatedpolydimethylsiloxane can be prepared in various amounts, optionally witha catalyst and a crosslinker in a high viscosity solvent. In general,the vinyl-functionalized organopolysiloxane can be added to thecomposition in a range of about 2 wt. % to about 25 wt. %, and morepreferably in a range of about 9 wt. % to about 19 wt % Likewise thehydroxyl terminated polydimethylsiloxane can be added to the compositionin a range of about 2 wt. % to about 25 wt. %, and more preferably in arange of about 9 wt. % to about 19 wt. %. A high vapor pressure, lowboiling point solvent, such as the HFE solvent can be added to thecomposition in a range of about 65 wt. % to about 85 wt. %, and morepreferably in a range of about 70 wt. % to about 80 wt. %. In someembodiments, a catalyst and a crosslinker can be added to thecomposition. For example, a catalyst such as Momentive® Product Code No.SS8010 platinum catalyst, can be added in a range of about 0.002 wt. %to about 0.070 wt. %, and more preferably in a range of about 0.008 wt.% to about 0.05 wt. %. A crosslinker such as Momentive® Product Code No.SS4300 crosslinker, can be added in a range of about 0.01 wt. % to about0.40 wt. %, and more preferably in a range of about 0.04 wt. % to about0.28 wt. %.

Alternatively, the single, homogeneous coating composition can beprepared by combining the base coating and the top coating (bothdescribed above) in various ratios. Separate batches of each coating canbe made and various amounts of the coating can be combined. For example,the ratio of the base coating to the top coating can be in the range ofabout 1:5 to 5:1, and more preferably in the range of about 1:3 to 3:1,for example, about 1:2, 1:1, 2:1, 1:3, 3:1, etc. As will be appreciatedby those having ordinary skill in the art, any ratio combination of thetop and base coatings can be used, including fractional ratios such asabout a 0.5:1, a 1:0.5, a 1:1.5, a 1.5:1, a 1:2.5, a 2.5:1, etc.

In some embodiments, the single, homogeneous coating can be formed froma mixture of about 18.38 wt. % of the base silicone polymer, forexample, the vinyl-functionalized organopolysiloxane, combined withabout 72.85 wt. % of the HFE solvent. The base silicone polymer and theHFE solvent can be combined with about 8.667 wt. % of the siliconepolymer, for example, the hydroxyl terminated polydimethylsiloxane. TheMomentive® SS8010 platinum catalyst can then be added to the mixture ina suitable amount (e.g., about 0.0165 wt. %) and the Momentive® SS4300crosslinker can be added at a suitable amount (e.g., about 0.0936 wt.%). The mixture can be agitated for a few minutes to ensure homogeneity,for example, for about one to two more minutes. This mixture isequivalent to, for example, about a 2:1 ratio (by weight) of the baseand top coatings.

In another embodiment, an exemplary single, homogeneous coating can beformed from a mixture of about 13.78 wt. % of the base silicone polymer,for example, a vinyl-functionalized organopolysiloxane, combined withabout 73.13 wt. % of the HFE solvent. The base silicone polymer and theHFE solvent can be combined with about 13.00 wt. % of the siliconepolymer, for example, hydroxyl terminated polydimethylsiloxane. Thecatalyst can then be added to the mixture at about 0.0124 wt. % and thecrosslinker can be added at about 0.0702 wt. %. This mixture isequivalent to, for example, about a 1:1 ratio (by weight) of the baseand top coating solutions.

In still a further embodiment, the single, homogeneous coating can beformed from a mixture of about 9.189 wt. % of the base silicone polymer,for example, a vinyl-functionalized organopolysiloxane, combined withabout 73.42 wt. % of the HFE solvent. The base silicone polymer and theHFE solvent can be combined with about 17.33 wt. % of the siliconepolymer, for example, hydroxyl terminated polydimethylsiloxane. Thecatalyst can then be added to the mixture at about 0.083 wt. % and thecrosslinker can be added at about 0.0468 wt. %. This mixture isequivalent to, for example, about a 1:2 ratio (by weight) of the baseand top coating solutions.

As will be appreciated by those skilled in the art, there are variousconventional methods of mixing the base and top coating solutionsutilizing conventional processing equipment and techniques to achievethe different weight ratios within the single, homogeneous coating. Inone method of mixing, master batches of the base coating and the topcoating can each be mixed. The appropriate ratios of each coating canthen be mixed together from the master batches to form the single,homogeneous coating. For example, if single, homogeneous coating withabout a 2:1 ratio mixture of the base coating and the top coating aredesired, then an amount of top coating can be mixed with double theamount of base coating, for example, about 20 grams of the base coatingmixed with about 10 grams of the top coating. Or, if a single,homogeneous coating with about a 1:1 ratio is desired, then equal partsof the base and top coating can be mixed. In another embodiment, thecombined single, homogeneous coating can be made directly with allcomponents being added directly in their correct proportion, rather thanmixing from separate master batches of the top and base coatings.

In some embodiments, a primer coating can optionally be applied to amedical device before the single, homogeneous coating. As noted above,the primer coat can have any formulation capable of bonding to a medicaldevice and capable of providing an appropriate substrate for applyingthe single, homogeneous coating. In one embodiment, the primer coat canbe formed of, for example, polyalkylsiloxane and tetraethyl silicate. Apolyalkylsiloxane and tetraethyl silicate primer coat can be formulatedfor coating difficult-to-bond substrates such as, for example,tungsten-rhenium alloys. In other embodiments, a primer coating is notdesired or required, and the single, homogeneous coating is applieddirectly to the substrate, i.e., the surface, of the medical device andis the only coating applied to the medical device. In still furtherembodiments, a surface of the medical device can include a primercoating as a part thereof and/or preformed thereon such that when thesingle, homogeneous coating is applied, there is only a single coatinglayer on the medical device.

The single, homogeneous coating can generally be applied at anythickness as needed. The thickness of the single, homogeneous coatingshould be sufficient to effectively provide the desired characteristics.For example, the single, homogeneous coating can be applied with athickness in the range of about 1 μm to about 12 μm and more preferablyfrom about 3 μm to about 6 μm or from about 1 μm to about 3.5 μm. If aprimer coat is applied, it can be applied to have a thickness in therange of about 0.01 μm to about 1 μm. A person skilled in the art willappreciate that the thickness of the single, homogeneous coating and/orthe primer coat can vary depending on a particular application.

There are many methods and systems contemplated herein that can be usedto provide coated surgical needles or other medical devices. In general,a medical device such as a surgical needle can be produced from adesired material and prepared for coating, as described in more detailbelow. One or more coatings can be applied to the surgical needle toprovide durability and lubricity during use. Before, during, and/orafter application of any one of the coatings, the surgical needle can becured for a sufficient amount of time effective to remove solvents inthe coatings and/or to set, crosslink, and/or bond a coating.

Any process known in the art can be used to coat various medical deviceswith one or more of a base coat, a top coat, a single coat composed of amixture of a base coat and a top coat (or the components of the base andtop coat), and/or a primer coat including, but not limited to, dipping,spraying, wiping, brushing, total immersion, gravity feed, etc. Forexample, surgical needles can be dip coated in a number of traditionalways. If needles are being processed manually, the needles can be handdipped or totally submersed in a coating. In a more automated process,coating solutions can be applied using a weir type circulating system inwhich surgical needles pass through the solution in an automaticfashion, either by robot or handling system. Dip techniques generallyrely on surface tension for adhesion of the coating and wettingcharacteristics of the coating with relation to the substrate forcontinuity. A person skilled in the art will appreciate the variouspossible conventional processes, process equipment, and equivalentsthereof, that can be used for the various techniques.

In one embodiment, one or more coatings can be applied to a surgicalneedle by spraying using, for example, ultrasonic and/or gas conformalcoating spray nozzle systems and/or swirl coating systems. Ultrasonicand gas spray nozzles transmit energy to a liquid in an amountsufficient to atomize the liquid and form a spray of droplets. The sprayof droplets can be applied to a medical device using a swirl process inwhich the droplets are swirled around the medical device in order tocoat the substrate. Application of a coating using the swirl process canensure a more even distribution of the coating to a surgical devicewhile preventing excess collection of the coating that may result indrips, undesired pooling, droplets, and/or unevenness. Spraying alsoallows for precise control and adjustment of coating thickness. Aparticular coating can be applied to leave only a thin film on a surfaceor it can be applied to provide different thicknesses.

Different types and sizes of spray nozzles can be used depending on thespecific coating compositions and the desired attributes of the spraystream generated. Spray nozzles can be designed to operate at specificfrequencies and/or air pressures as needed and the desired power levelfor operating the nozzles can depend on various factors including thesize and design of the nozzle, the viscosity of the composition beingused, the volatility of components in the composition being used, etc.Both ultrasonic and fluid spray nozzles are available commercially.

In one embodiment, such as those illustrated in FIGS. 3A and 3B, opposedspray nozzles 30 a, 30 b are provided for applying a swirl coating toexemplary surgical needles 32. The opposed spray nozzles 30 a, 30 b caneach be coupled to canisters holding a particular coating to be appliedand can deliver the coating through discharge openings 31 a, 31 b. Eachcoating to be applied by the swirl process can be applied usingdifferent pairs of opposed spray nozzles 30 a, 30 b. Thus, in someembodiments, multiple sets of spray nozzles can be used to applymultiple coatings. Each spray nozzle 30 a, 30 b can have a fluted tip(not shown) for delivering the coating. An angle of the fluted tip,relative to a horizontal plane through which the needles extendperpendicular to, can be adjusted to focus the band of spray to optimizecoating. As will be appreciated in the art, any angle can be used asneeded to deliver a particular coating. In addition, different coatingsmay require delivery from a fluted tip with a different angle.

The opposed pair of spray nozzles 30 a, 30 b can extend from apositioner (not shown) capable of adjusting and maneuvering the spraynozzles 30 a, 30 b in three dimensions. The opposed spray nozzles 30 a,30 b can be positioned in any way relative to each other as needed for aparticular application and can generally be symmetrically opposed to oneanother. In the illustrated embodiment, the spray nozzles 30 a, 30 b arepositioned at approximately about a 30 degree angle, as shown in FIGS.3A-3B, relative to a horizontal surface. Horizontally, the nozzles 30 a,30 b can be directly opposed, e.g., offset by about 180 degrees.Preferably, however, the nozzles 30 a, 30 b can be horizontally offsetrelative to each other by an amount less than about 180 degrees toprevent neutralization and to prevent overspray from collecting on theneedles. The positioning of the opposed nozzles 30 a, 30 b can beoptimized to provide the most complete coating of a surgical needle.

In general, the swirl coating can be applied during relative movementbetween the needles 32 and the nozzles 30 a, 30 b. In some embodiments,one or more needles 32 can remain stationary while the nozzles 30 a, 30b move relative to the needles 32 while spraying the coating. In otherembodiments, a carrier strip, such as the carrier strip 20 shown in FIG.2, or a carrier strip 40 shown in FIGS. 3A and 3B, can move a pluralityof surgical needles 32 relative to the opposed spray nozzles 30 a, 30 bwhile the nozzles 30 a, 30 b remain stationary. In other embodiments,both the carrier strip 40 and the nozzles 30 a, 30 b can move relativeto one another. The carrier strip 40 can be mounted below the nozzles 30a, 30 b as shown in FIG. 3A, or the carrier strip 40 can be mountedabove the nozzles 30 a, 30 b as shown in FIG. 3B.

The movement speed of the carrier strip 40 and/or the nozzles 30 a, 30 bcan be controlled so that the spray nozzles 30 a, 30 b provide optimalcoverage and coating of the needles 32. For example, relative movementspeed between the needles 32 and the nozzles 30 a, 30 b can be in therange of about 1 to about 15 inches per second. Optimally, the relativemovement speed can be in the range of about 3 inches per second to about5 inches per second. Shields may be optionally disposed between thenozzle discharge openings 31 a, 31 b and the proximal portion of theneedle.

In some embodiments, a single, homogeneous coating can be applied to amedical device, such as a surgical needle, using the spray nozzles 30 a,30 b. As noted above, when a single, homogeneous coating is utilized, itcan be a mixture of the top and base coating described herein and/or amixture of components designed to provide both lubricousness anddurability. There are a number of ways that the single, homogeneouscoating can be applied using the spray nozzles 30 a, 30 b. For example,the single, homogeneous coating can be premixed to the correct weightratio of top and base coatings, for example, about 2:1 ratio, 1:1 ratio,and/or 1:2 ratio, and the premixed composition can be delivered by thenozzles 30 a, 30 b in a single, homogeneous coating layer on the medicaldevice.

In another embodiment, the top coating can be delivered by one nozzle 30a, and the base coating can be delivered by the other nozzle 30 b. Inthe case where about a 2:1 ratio of the top and base coatings isrequired, or about a 1:2 ratio of the top and base coatings is required,one nozzle 30 a, 30 b can be configured to deliver an amount of onecoating while the other nozzle 30 b, 30 a is configured to deliver adifferent the amount (e.g., double or half of the amount) of the othercoating such that the weight ratios are as desired.

In still a further embodiment, the top and base coatings can be providedinto canisters in fluid communication with the nozzles 30 a, 30 b andthe two coatings can be mixed into the desired ratio within the nozzles30 a, 30 b prior to being applied to the medical device. For example,the nozzles 30 a, 30 b can have a mixing mechanism, such as two feedlines, associated therewith that can mix about a 2:1 ratio, a 1:1 ratio,a 1:2 ratio, and/or any other ratio desired, of the top and basecoatings such that the single, homogeneous coating is premixed withinthe nozzles 30 a, 30 b before it is applied to the medical device.

There are many mechanisms known in the art for curing, hardening, and/orsetting a coating on a surgical device such a surgical needle. Curingcan also cause evaporation of any solvent used in making the coating.Curing can generally be accomplished through exposure of a coatedsurgical needle to some form of temperature increase and/or humiditychange for a predetermined period of time. For example, the coatedneedles can be placed in a furnace or oven, a hotbox, a humidificationchamber, and/or an infrared chamber, among other forms known in the art.Curing times can range from “flash” curing of only a few seconds totimes longer than twenty-four hours.

During the curing process, the temperature and/or humidity can bemaintained at a single value for the entire time and/or it can beincreased or decreased as needed over time. Temperature can be monitoredand adjusted using, for example, a thermocouple and a potentiometer tocontrol power to heating elements. The potentiometer can bepreconfigured so that temperature measurements made by the thermocoupleat periodic increments along a length of the heating system aremaintained at or between a specified temperature range. In otherembodiments, temperature can be controlled using a feedback loop wheretemperature measurements that correlate to temperatures where surgicalneedles will pass are fed back to a power supply that continuouslyadjusts power delivered to the heated filaments to maintain a desiredtemperature range. A humidity monitor can be used to monitor and adjusthumidity. In some embodiments, each coating can be cured afterapplication thereof to the surgical needle. In other embodiments, allcoatings can be applied before initiating the curing process.

In one embodiment, an infrared emitter can be used to effect curing of acoating. Infrared emitters are available commercially from Heraeus®Noblelight, for example, Model SKL200-800. The actual emitters caninclude, for example, eight foot long thin heated filaments embeddedwithin a reflective channel used to focus and contain the heat. Theinfrared heating system can be oriented so that the channel's opening isfacing down. Surgical needles to be cured in the infrared heating systemcan be held vertically and passed between two concave reflective wallsof the channel at about, for example, ¼ inch from the heated filaments.Needles can be held on a carrier strip as they traverse the channel at aspeed in the range of about 3 inches per second to about 5 inches persecond, although any speed can be used.

While many methods for providing durable lubricious coatings on surgicalneedles are contemplated, a flow chart of an embodiment of oneparticular method is illustrated in FIG. 4A. As shown, the method cangenerally include manufacturing the surgical needles, preparing thesurface of the needles for receiving a coating, coating the needles witha primer coat, base coat, and/or top coat, and curing the coatings. Inanother embodiment illustrated in FIG. 4B, the method can generallyinclude manufacturing the surgical needles, preparing the surface of theneedles for receiving a coating, optionally coating the needles with aprimer coat, coating the needle with a single, homogeneous coating, andcuring the single, homogeneous coating. A person skilled in the art willappreciate the variations and additions that can be included in suchmethods.

In manufacturing the surgical needles, raw wire of a suitablecomposition can be unspooled and cut into blanks for shaping. While anysize blanks can be used depending on the size of the needle desired, inone embodiment, the wire can be cut into two inch blanks. Once cut, theblanks can be attached to a metal carrier strip, such as thatillustrated in FIG. 2. The blanks can be secured and shaped into theirpreferred needle form by any methods known in the art, includingforming, grinding, curving, etc.

Needles that are appropriately shaped can be cleaned to removecontaminates and to prepare the surface for receiving a coating. Forexample, the needles can be exposed to high pressure nozzles thatrelease water at high temperature and pressure. In other embodiments,the needles can be baked to high temperatures to release anycontaminates. Once the needles have been cleaned, they can beelectropolished for any amount of time necessary. The needles can beimmersed in the electropolish bath (e.g., sodium hydroxide, phosphoricacid, etc.) and subjected to direct current to remove ions at acontrolled rate. Once complete, the needles can be rinsed successivetimes, for example, two times, in de-ionized water baths.

In some embodiments, a primer coat, such as the SS4044P primer describedabove, can be applied to the newly manufactured and cleaned surgicalneedles. The primer coating can be used, for example, when the needle isa tungsten-rhenium alloy. The primer can be applied using any methodknown in the art including dipping or spraying, but in one embodiment,the primer is applied to the surgical needles by dipping. Using agrasper or carrier strip, the needles can be dipped into the primer atroom temperature for one to two seconds to effect complete coveragethereof. A person skilled in the art will appreciate that primers can beapplied at any temperature and for any length of time as appropriate fora particular primer. Reactive functional groups in the primer can reactwith the functional hydroxide groups in the surface of the surgicalneedles and covalently bond thereto. In some embodiments, after theprimer coating has been applied, the surgical needle can be flash curedfor about 20 seconds at an appropriate temperature, for example, about200 degrees Celsius. Once cured, the primer can create a boundarybetween the surface of the surgical needle and any later appliedcoatings.

In some embodiments, a base coat, such as the Momentive® base coatdescribed above, can be applied to the external surface of the surgicalneedle, and over a primer if utilized, for example, the SS4044P primer.Any application method known in the art can be used, but in oneembodiment, the surgical needle is sprayed or swirl coated with the basecoat using opposed spray nozzles. For example, the surgical needle canbe passed between first and second opposed spray nozzles to be coated.Application of the base coat using the spray or swirl coating ensures anevenly distributed layer of the base coat on the needle or over theprimer, if utilized. As the base coat is applied, the solvent, forexample, the HFE solvent, can rapidly evaporate to leave a thin layer ofevenly distributed silicone on the needle surface. In some embodiments,the base coat can be cured onto the surface by exposure to an “in-line”infrared heating system. The base coat can be exposed to a number ofdifferent wavelengths of infrared light and cured.

The coated medical device of the invention may also have a top coatapplied over the base coat, more preferably after the base coat ispartially cured. For example, the NuSil® top coat described above can beapplied over the Momentive® base coat. Any application method known inthe art can be used, but in one embodiment, the surgical needle can besprayed or swirl coated with the top coat using opposed spray nozzles.For example, the surgical needle can be passed between third and fourthopposed spray nozzles to be coated. Application of the top coat usingthe spraying or swirl coating technique ensures an evenly distributedlayer of the top coat over the base coat. As the top coat is applied,the solvent, for example, the HFE solvent, can rapidly evaporate toleave a thin layer of evenly distributed top coat over the base coat. Insome embodiments, after application of the top coat, the top coat can beflashed cured to drive off any excess solvent. The needles can be passedthrough, for example, a hot box or other heated curing system, for anytime and at any temperature necessary to accomplish evaporation of thesolvent. In one embodiment, the top coat can be flashed cured in aninfrared heater for approximately 20 seconds at a temperature in therange of about 165 degrees Celsius to about 200 degrees Celsius.

In other embodiments, a single, homogeneous coating can be applied tothe external surface of the surgical needle, and over a primer ifutilized, for example, the SS4044P primer. The single, homogeneouscoating can be, for example, a combination of the Momentive® base coatand the NuSil® top coat described above, although any suitablecombination of materials can be used to form the single, homogeneouscoating. Any application method known in the art can be used, but in oneembodiment, the surgical needle is sprayed or swirl coated with thesingle, homogeneous coating using opposed spray nozzles. For example,the surgical needle to be coated can be passed between first and secondopposed spray nozzles. Application of the single, homogeneous coatingusing the spray or swirl coating ensures an evenly distributed layer ofthe single, homogeneous coating on the needle or over the primer coat ofthe needle, if utilized. As the single, homogeneous coating is applied,the solvent, for example, the HFE solvent, can rapidly evaporate toleave a thin layer of the single, homogeneous coating on the needlesurface. In some embodiments, the single, homogeneous coating can becured by exposure to an “in-line” infrared heating system for asufficiently effective period of time such as, for example, from about 1second to about 60 seconds, from about 10 seconds to about 30 seconds,and/or for about 20 seconds. The single, homogeneous coating can beexposed to a number of different wavelengths of infrared light andcured. The single, homogeneous coating can also be cured in an oven at atemperature in the range of about 60 degrees Celsius to about 180degrees Celsius for a time in the range of about 1 hour to about 5hours, from about 2.5 hours to about 3.5 hours, and/or more preferablyfor about 3 hours at a temperature in the range of about 100 degreesCelsius to about 140 degrees Celsius.

Following application of the top coat and/or of the single, homogeneouscoating, the surgical needles can be optionally re-spooled. In someembodiments, the coated surgical needles can be exposed to a finalcuring process. For example, the re-spooled needles can be placed insidea convection oven and cured at a temperature and time sufficient tofurther cure the coating. In one embodiment, the surgical needles can becured in the convection oven for approximately four hours at about 165degrees Celsius. In other embodiments, the final cure can be performedat a temperature of about 80 degrees Celsius for approximately threehours.

The cure times for the exemplary coatings and methods described hereinare extremely beneficial in that they are significantly less than curetimes for previous coatings and methods known in the art. Previouscoatings and methods could require curing of the surgical needles for upto 72 hours plus processing and coating time. The currently describedexemplary coatings and methods can reduced the total curing time to lessthan about 4 hours and possibly less than about 15 minutes, providing asignificant increase in efficiency for manufacturing of the needles.With the use of the single, homogeneous coating, the cure time can bereduced even further to less than about 1 minute.

The use of two coatings as described above, and/or of a single, forexample, continuous coating as also described above, results in surgicalneedles that exhibit reduced and/or generally constant tissuepenetration force compared with standard surgical needles after anequivalent number of passes through tissue. Thus, both the lubricity ofthe needle as well as the durability of the coating is improved. Thiseffect is believed to result for a number of reasons. For example,application of the base and top coats using a swirl coating processprovides an even distribution of the coatings over the substrate. Thisis most clearly represented in FIG. 6, which will be described in moredetail below. In addition, the compositions of the coatings incombination with the methods of application and curing can result insignificantly decreased average force required to repeatedly pass theneedle through synthetic media, as shown in FIG. 7, which will also bedescribed in more detail below.

The use of the optional primer coating can also be advantageous. Aprimer coating can be capable of chemically bonding to the needlesurface to provide a bonding substrate for the lubricious siliconecoatings to adhere to, resulting in increased durability of the base andtop coatings. For example, FIG. 5 illustrates the force required to passa needle through synthetic media in relation to the number of passesthrough synthetic media. As shown, needles without primer have a drasticrise in the force required after thirty passes when compared with primedneedles of identical material and configuration, which tend to maintaina fairly constant force up to at least thirty passes through syntheticmedia. More detail will be presented in the examples described below.

Coating performance for medical devices can generally be tested with avariety of conventional tests. In the case of surgical needles, coatingperformance and integrity is evaluated using a penetration test device.A portion of a coated surgical needle is held using a holding device,and the coated needle is then partially passed through a synthetic ornatural penetratable material some number of times. The material istypically a type of polymer or synthetic leather, for example, Permair,Rubber-Cal, Monmouth rubber, Porvair, etc. The needle can be passedthrough the penetratable material for about one to about twenty times,between about one to about twenty-five times, and most preferablybetween about one to about thirty times. The needle is then retractedfrom the media. The maximum force is recorded for each pass and is usedas a measure of the coating performance. Various attributes of coatingperformance can be tested using these techniques.

EXAMPLES

The following experiments were conducted to examine the effects ofvarying the needle coating materials and methods. For each test, theneedles were passed through Monmouth Duraflex MR40 NBR rubber membrane(“Monmouth rubber”), which serves to simulate flesh, or human cadavertissue. In the following non-limiting examples, from 4 to 10 needleswere used and individually passed through the penetration membranethirty times each. The maximum force in grams was recorded for each passand used as a measure of coating performance.

The surgical needles were mounted in a rotating stage to fix the needlein a position perpendicular to the penetration membrane surface andoriented on its radial profile with the axis of rotation on the sameplane as the plane of the penetration membrane. The needle was rotatedinto the penetration membrane, which was mounted on top of the loadcell. The maximum amount of vertical force was recorded as the needlewas pushed through the penetration membrane.

The following non-limiting examples serve to further illustrate theprinciples and practice of the present invention:

Example 1

The following tests were performed to examine the effect coating methodshave on the force required to pass a needle through Monmouth rubbersynthetic media. The performance of needles that were dip coated wascompared with the performance of needles that were spray/swirl coated.

TEST A

In Test A, five needles were prepared for penetration testing. Theneedles were made from ETHALLOY® Alloy stainless steel and had adiameter of 0.0105 inches. A base coating composition was prepared froma mixture of 20 wt. % of Micropro 600 and Micromatte 2000, produced byMicropowders Inc., mixed with 80 wt. % of HFE-72DE solvent. The MicroProand Micromatte powder weight ratio was at 4:1. Five test needles wereeach dipped into the base coating to coat their surfaces. The needleswere coated by hand via the dipping process and placed on a magnetictray. The tray includes raised magnetic strips for holding the proximalends of the needles secure during the curing cycle and transport whilethe distal end (tip) of the needles hang over the edge of the magneticstrips. This configuration prevents the needle tips from making contactwith the tray. The coated needles were then heated to 190 degreesCelsius in a convection oven for ninety minutes at ambient atmosphere.The needles were then allowed to cool at ambient temperature outside ofthe oven.

A top coating composition was prepared using 26 wt. % of NuSil® MED4162with 74 wt. % HFE-72DE solvent. The five needles were then each handdipped into the top coating composition. The needles were then heated to220 degrees Celsius in a convection oven and cured for four hours atambient atmosphere. The needles were allowed to cool at ambienttemperature outside of the oven.

Once cured, the five needles were each passed through the penetrationmembrane thirty times and the penetration force in grams was recorded asshown in Table 1 below.

TABLE 1 Pass ---> Penetration [g] Experiment Needle 1 2 3 4 5 6 7 8 9 1011 12 13 14 15 A 1 39 38 41 40 42 47 42 46 43 47 47 46 48 49 52 2 40 4245 46 46 49 50 55 51 51 56 53 56 57 63 3 40 41 41 47 45 46 49 51 51 4550 52 52 57 54 4 34 34 36 36 36 36 38 37 40 39 42 41 44 43 45 5 38 38 3840 42 44 47 45 48 48 46 50 49 52 51 St Dev 2.5 3.1 3.4 4.6 3.9 5.0 5.16.8 4.9 4.5 5.2 4.9 4.5 5.9 6.5 Avg 38.2 38.6 40.2 41.8 42.2 44.4 45.246.8 46.6 46.0 48.2 48.4 49.8 51.6 53.0 Pass ---> Penetration [g]Experiment Needle 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 A 1 53 4553 57 48 56 53 55 56 54 57 57 57 60 61 2 59 54 64 62 65 69 62 66 68 6871 75 73 72 69 3 56 55 58 56 57 60 61 59 62 61 61 62 60 64 62 4 45 45 4648 49 48 49 51 53 53 50 53 52 56 53 5 51 51 52 50 54 51 56 52 57 59 5358 61 58 58 St Dev 5.3 4.8 6.8 5.6 6.9 8.2 5.4 6.1 5.9 6.0 8.2 8.5 7.86.3 5.9 Avg 52.8 50.0 54.6 54.6 54.6 56.8 56.2 56.6 59.2 59.0 58.4 61.060.6 62.0 60.6

TEST B

In Test B, five needles were prepared for penetration testing. Theneedles were made from ETHALLOY® Alloy stainless steel and had adiameter of 0.0105 inches. A base coating composition was prepared froma mixture of 20 wt. % of Micropro 600 and Micromatte 2000, produced byMicropowders Inc., mixed with 80 wt. % of HFE-72DE solvent. The MicroProand Micromatte powder weight ratio was at 4:1. The five test needleswere swirl coated with the base coating composition using a single passspray using the SC-300 Swirl Coat™ Applicator and the Century® C-341Conformal Coating System available from Asymtek® of Carlsbad, Calif.with the following parameters: 2 PSI fluid pressure, 50 PSI air assist,and 10 in/sec line speed. The coated needles were then heated to 190degrees Celsius in a convection oven and cured for ninety minutes atambient atmosphere. The needles were allowed to cool at ambienttemperature outside of the oven.

A top coating composition was prepared using 26 wt. % of NuSil® MED4162with 74 wt. % HFE-72DE solvent. The five test needles were swirl coatedwith the top coating composition using a single pass spray with thefollowing parameters: 10 PSI fluid pressure, 50 PSI air assist, and 5in/sec line speed. The needles were then cured for four hours at 220degrees Celsius. Once cured, the five needles were each passed throughthe penetration membrane thirty times and the penetration force in gramswas recorded as shown in Table 2 below.

TABLE 2 Pass ---> Penetration [g] Experiment Needle 1 2 3 4 5 6 7 8 9 1011 12 13 14 15 B 1 30 29 30 31 31 31 33 33 31 32 34 34 34 35 36 2 33 3231 35 33 34 34 35 34 35 35 36 36 35 37 3 29 28 30 29 30 30 31 31 32 3232 33 34 32 32 4 29 29 29 28 29 30 31 30 32 33 33 33 35 35 34 5 32 31 3333 32 32 35 34 34 33 34 35 36 35 36 St Dev 1.8 1.6 1.5 2.9 1.6 1.7 1.82.1 1.3 1.2 1.1 1.3 1.0 1.3 2.0 Avg 30.6 29.8 30.6 31.2 31.0 31.4 32.832.6 32.6 33.0 33.6 34.2 35.0 34.4 35.0 Pass ---> Penetration [g]Experiment Needle 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 B 1 34 3837 36 37 38 37 38 37 40 40 39 37 39 42 2 37 37 39 38 38 37 38 39 38 3940 39 40 40 41 3 35 33 33 34 35 34 35 35 36 35 34 34 36 36 37 4 36 36 3737 38 38 38 39 39 38 40 41 41 38 41 5 38 36 37 34 37 37 36 37 37 37 3939 38 39 39 St Dev 1.6 1.9 2.2 1.8 1.2 1.6 1.3 1.7 1.1 1.9 2.6 2.6 2.11.5 2.0 Avg 36.0 36.0 36.6 35.8 37.0 36.8 36.8 37.6 37.4 37.8 38.6 38.438.4 38.4 40.0

FIG. 6 is a graphical representation of the averaged results of Tests Aand B in direct comparison. The y-axis shows the penetration force ingrams needed to pass a needle through the penetration membrane. Thex-axis shows the number of passes. The thick solid line represents theneedles that were dip coated with the base and top coating compositions,as set forth in Test A, while the thin solid line represents the needlesthat were swirl coated with the base and top coating compositions, asset forth in Test B.

As can be seen, the needles that were dip coated had an initialpenetration force of about 38 g. The penetration force increasedsteadily over the thirty passes, and the needles required an averagemaximum force of 61 g after thirty passes. In contrast, the needles thatwere swirl coated had an initial penetration force of about 31 g. Thepenetration force remained substantially constant over the thirtypasses, with the average maximum force after thirty passes being about40 g. As shown, the needles that were swirl coated required about 7 gless force in the beginning on average than the needles that were dipcoated, and the force remained substantially constant. Ultimately, theswirl coated needles required about 21 g less maximum force after thirtypasses than the dip coated needles.

Example 2

The penetration performance of various coating compositions and coatingmethods were also tested. In the following Tests A and B, two differenttypes of needle coating compositions and application methods wereexamined. The needles were passed through Monmouth rubber syntheticmedia.

TEST A

In Test A, ten commercially available Ethicon BV-175 surgical needleshaving a 0.0078 inch diameter were tested. A coating was applied using adouble dipping procedure. In particular, a silicone dip was preparedusing a concentration of NuSil® Product No. MED4162 mixed with Micropro600 and Micromatte 2000 powders for lubrication as described above. Theneedles were placed on a moving carrier strip and dipped a first time.The needles were then flash cured in a hot box at approximately 225degrees Celsius for thirty seconds. The needles were then cured for 36hours in a convection oven at 163 degrees Celsius. The needles weredipped a second time, flash cured, and then cured in a convection ovenfor another 36 hours.

As shown in Table 3 below, ten needles were tested with thirty passesthrough the penetration membrane.

TABLE 3 Pass ---> Penetration [g] Experiment Needle 1 2 3 4 5 6 7 8 9 1011 12 13 14 15 A 1 35 38 37 38 38 38 38 39 38 38 40 40 41 42 41 2 35 3737 37 38 39 40 40 39 40 38 40 41 40 39 3 26 26 27 28 28 28 28 29 29 3031 31 31 30 34 4 28 29 31 32 32 32 32 33 33 33 34 34 34 33 34 5 28 34 3132 33 34 35 34 34 34 34 35 35 35 36 6 27 28 28 31 30 30 31 32 32 32 3434 35 32 34 7 34 35 36 37 38 37 38 38 38 39 39 40 40 39 41 8 27 34 32 3334 34 35 35 36 37 38 37 40 39 38 9 25 28 27 29 30 31 31 33 34 35 35 3637 37 36 10 25 27 29 30 29 31 31 30 31 31 31 32 32 33 34 St Dev 4.1 4.54.0 3.5 3.9 3.7 3.9 3.7 3.3 3.5 3.2 3.3 3.7 4.0 2.9 Avg 29.0 31.6 31.532.7 33.0 33.4 33.9 34.3 34.4 34.9 35.4 35.9 36.6 36.0 36.7 Pass --->Penetration [g] Experiment Needle 16 17 18 19 20 21 22 23 24 25 26 27 2829 30 A 1 40 40 42 43 42 40 42 42 43 42 44 43 41 40 43 2 44 39 43 39 4140 40 44 40 43 42 40 40 42 40 3 31 33 30 32 34 33 33 34 35 34 33 34 3534 35 4 36 35 36 37 38 37 36 35 36 38 38 38 38 38 38 5 36 35 36 38 37 3737 38 38 40 38 39 36 38 38 6 35 33 35 35 36 34 35 35 35 36 36 36 36 3636 7 41 41 40 40 40 41 41 42 42 40 42 42 45 41 41 8 39 41 40 39 40 40 4142 40 40 42 43 43 40 40 9 38 40 39 40 42 42 42 43 43 46 46 43 45 46 4610 34 33 34 33 34 33 34 34 34 35 34 34 36 36 34 St Dev 3.8 3.5 4.0 3.43.1 3.4 3.5 4.1 3.5 3.7 4.4 3.6 3.9 3.5 3.7 Avg 37.4 37.0 37.5 37.6 38.437.7 38.1 38.9 38.6 39.4 39.5 39.2 39.5 39.1 39.1

TEST B

In Test B, ten Ethicon tungsten-rhenium alloy needles having an 0.008inch diameter were tested. The needles were prepared by applying theMomentive® SS4044P primer coat at room temperature. The primer coat wasflash cured at 200 degrees Celsius for 2-3 seconds. A base coatingcomposition was then applied over the primer using swirl coatingtechniques. The base coating composition was made by combining 27.58 wt.% of Momentive®, vinyl siloxane polymer, product no. MSC2631, with 72.25wt. % of the HFE 72-DE solvent and agitated for about five minutes.Momentive®, catalyst in toluene, product no. SS8010, was then added tothe mixture at 0.02 wt. %, and Momentive®, polymethyl hydrogen siloxane,product no. SS4300 was added at 0.14 wt. %. The base coating was appliedto the surgical needles using the Asymtek C-341 Conformal Coater and theAsymtek SC-300 Swirl Applicator. The needles were then heated to 300degrees Celsius for thirty seconds in an infrared heater.

A top coating composition was then applied to the needles and was formedfrom 26 wt. % of the NuSil® MED4162 silicone product combined with 74wt. % of the HFE 72-DE solvent. The top coating composition was alsoapplied using swirl coating techniques with the Asymtek C-341 ConformalCoater and the Asymtek SC-300 Swirl Applicator. The needles were againflash cured at a temperature of 190 degrees Celsius for approximatelythirty seconds.

The needles included in Test B were then batch cured at 80 degreesCelsius for three hours in a convection oven. The needles were tested bypassing each needle thirty times through the penetration membrane. Theforce required to do so is set forth in Table 4.

TABLE 4 Pass ---> Penetration [g] Experiment Needle 1 2 3 4 5 6 7 8 9 1011 12 13 14 15 B 1 22 22 22 23 23 22 22 23 21 23 23 22 22 22 22 2 22 2423 23 22 21 22 22 22 23 24 23 23 22 23 3 21 21 23 22 21 21 20 22 22 2122 21 21 22 22 4 21 21 22 22 24 23 24 24 25 23 23 24 24 24 24 5 21 21 2223 22 22 21 22 21 22 22 22 22 22 22 6 20 22 22 22 22 24 22 22 22 23 2322 22 22 23 7 21 23 22 22 21 22 22 23 22 23 21 23 22 22 22 8 21 23 22 2323 23 22 24 23 23 23 23 24 23 23 9 24 24 21 23 23 23 23 23 23 23 23 2324 25 24 10 21 21 21 20 20 21 21 20 21 21 22 21 21 22 21 St Dev 1.1 1.20.7 0.9 1.2 1.0 1.1 1.2 1.2 0.8 0.8 1.0 1.2 1.1 1.0 Avg 21.4 22.2 22.022.3 22.1 22.2 21.9 22.5 22.2 22.5 22.6 22.4 22.5 22.6 22.6 Pass --->Penetration [g] Experiment Needle 16 17 18 19 20 21 22 23 24 25 26 27 2829 30 B 1 21 22 23 23 23 22 24 22 22 23 22 23 23 24 23 2 23 24 23 24 2423 23 24 25 26 26 27 28 29 29 3 22 22 22 22 23 24 24 25 25 25 26 26 2628 28 4 26 25 24 24 24 24 25 26 25 25 25 26 26 25 26 5 22 22 23 23 23 2423 22 23 23 23 22 23 25 23 6 23 23 23 23 23 22 24 23 24 24 23 25 24 2424 7 23 22 23 23 23 24 23 23 23 25 24 23 25 25 24 8 22 23 23 24 24 24 2424 24 24 23 27 25 25 25 9 24 24 25 24 24 24 24 24 25 25 25 25 26 26 2610 22 22 21 22 22 22 22 22 23 22 23 23 24 24 23 St Dev 1.4 1.1 1.1 0.80.7 0.9 0.8 1.4 1.1 1.2 1.4 1.8 1.6 1.7 2.1 Avg 22.8 22.9 23.0 23.2 23.323.3 23.6 23.5 23.9 24.2 24.0 24.7 25.0 25.5 25.1

FIG. 7 is a graphical representation of the averaged results of Tests Aand B in direct comparison. The y-axis shows the penetration force ingrams needed to pass a needle through the penetration membrane. Thex-axis shows the number of passes. The thick solid line represents theneedles with conventional dip coating, as set forth in Test A, while thethin solid line represents the needles with the spray coating accordingto the present invention, as set forth in Test B.

As shown, the Test A needles initially required an average penetrationforce of about 29 g. The average penetration force for the Test Aneedles increased to 39 g after thirty passes. The Test B needles had aninitial average penetration force of 21 g and an average penetrationforce of 25 g after thirty passes.

Example 3

The following tests were performed to examine the effect coating methodshave on the force required to pass a needle through Monmouth rubbersynthetic media. The performance of needles that were dip coated wascompared with the performance of needles that were spray/swirl coated.

TEST A

In Test A, four 0.026 inch diameter needles made from ETHALLOY® Alloyand having a taper cut point geometry were prepared for penetrationtesting. A base coating composition was prepared from a solution of 2.5g of Momentive®, vinyl siloxane polymer, product no. MSC2631, 22.15 g ofExxon Isopar-K, 0.0022 g of Momentive®, catalyst in toluene, product no.SS8010, and 0.0127 of Momentive®, polymethyl hydrogen siloxane, productno. SS4300. Four test needles were each dipped into the base coatingcomposition to coat their surfaces. The coated needles were then heatedto 200 degrees Celsius in a convection oven furnace for one hour.

A top coat coating composition was prepared using 2.50 g of NuSil®MED4162 with 22.50 g of Exxon Isopar-K. The four needles were then eachdipped into the top coating composition. The needles where then heatedto 140 degrees Celsius in a convection oven and cured for three hours.

Once cured, the four needles were each passed through the penetrationmembrane thirty times and the penetration force in grams was recorded asshown in Table 5 below.

TABLE 5 A Pass → Penetration (g) Needle 1 2 3 4 5 6 7 8 9 10 11 12 13 1415 16 17 1 61 71 78 84 88 95 97 101 100 104 108 110 110 109 110 111 1112 65 67 70 73 76 79 82 83 84 84 86 90 90 90 90 92 93 3 60 69 75 80 85 8892 94 95 98 99 100 102 102 103 101 101 4 62 65 69 73 76 79 82 84 86 8889 92 92 94 95 95 95 STDEV 2 3 4 5 6 8 8 9 8 9 10 9 9 8 9 8 8 AVG 62 6873 78 81 85 88 91 91 94 96 98 99 99 100 100 100 A Pass → Penetration (g)Needle 18 19 20 21 22 23 24 25 26 27 28 29 30 1 112 110 112 114 112 113113 112 116 114 113 111 112 2 95 95 96 96 98 99 102 102 104 104 104 107109 3 104 107 104 103 104 104 103 105 107 107 105 108 108 4 97 124 121122 125 123 127 127 129 130 133 136 132 STDEV 8 12 11 12 12 11 12 11 1112 13 14 11 AVG 102 109 108 109 110 110 111 112 114 114 114 116 115

TEST B

In Test B, five 0.026 inch diameter needles made from ETHALLOY® Alloyand having a taper cut point geometry were prepared for penetrationtesting. The needles were prepared by applying a base coatingcomposition using swirl coating techniques. The base coating compositionwas made by combining 27.58 wt. % of the Momentive®, vinyl siloxanepolymer, product no. MSC2631, with 72.25 wt. % of the HFE 72-DE solventand agitated for about five minutes. Momentive®, catalyst in toluene,product no. SS8010, was then added to the mixture at 0.02 wt. %, andMomentive®, polymethyl hydrogen siloxane, product no. SS4300 was addedat 0.14 wt. %. The base coating was applied to the surgical needlesusing the Asymtek C-341 Conformal Coater and the Asymtek SC-300 SwirlApplicator. The needles were then heated to 300 degrees Celsius forthirty seconds in an infrared heater.

A top coating composition was then applied to the needles and was formedfrom 26 wt. % of the NuSil® MED4162 silicone product combined with 74wt. % of the HFE 72-DE solvent. The top coating composition was alsoapplied using swirl coating techniques with the Asymtek C-341 ConformalCoater and the Asymtek SC-300 Swirl Applicator. The needles included inTest B were then batch cured at 140 degrees Celsius for three hours in aconvection oven.

Once cured, the five needles were each passed through a Monmouth rubbersynthetic media thirty times and the penetration force in grams wasrecorded as shown in Table 6 below.

TABLE 6 B Pass → Penetration (g) Needle 1 2 3 4 5 6 7 8 9 10 11 12 13 1415 16 17 1 66 69 70 70 71 70 70 72 70 70 72 71 72 72 74 74 75 2 58 60 6061 61 61 63 62 63 62 63 64 64 64 62 64 66 3 56 56 57 57 58 58 58 58 5453 53 53 53 53 53 53 53 4 53 54 55 56 56 56 56 56 56 56 57 57 58 58 5858 58 5 56 57 59 61 56 57 58 59 58 59 60 60 60 59 57 59 59 STDEV 4.9 5.95.8 5.5 6.3 5.7 5.7 6.3 6.4 6.5 7.2 6.9 7.1 7.2 8.0 8.0 8.5 AVG 58 59 6061 60 60 61 61 60 60 61 61 61 61 61 62 62 B Pass → Penetration (g)Needle 18 19 20 21 22 23 24 25 26 27 28 29 30 1 76 76 76 76 76 76 75 7674 75 74 73 73 2 65 66 67 68 68 63 63 61 64 65 66 68 68 3 53 53 54 54 5455 55 55 56 56 56 57 58 4 58 58 58 60 60 59 60 60 60 60 61 61 61 5 60 6061 60 61 61 62 62 62 62 63 62 62 STDEV 8.7 8.8 8.6 8.5 8.4 7.9 7.4 7.96.7 7.2 6.7 6.3 6.0 AVG 62 63 63 64 64 63 63 63 63 64 64 64 64

FIG. 8 is a graphical representation of the averaged results of Tests Aand B in direct comparison. The y-axis shows the penetration force ingrams needed to pass a needle through the penetration membrane. Thex-axis shows the number of passes. The square points represent theneedles with the dip coating, as set forth in Test A, while the diamondpoints represent the needles with the spray coating according to thepresent invention, as set forth in Test B.

As shown, the Test A needles with the dip coating initially required anaverage penetration force of 62 g. The average penetration force for theTest A needles increased to 115 g after thirty passes. The Test Bneedles with the spray coating performed with an initial averagepenetration force of 58 g and resulted in an average penetration forceof 64 g after thirty passes. As can be seen, the needles in Test B withthe spray coating required significantly less penetration force up tothirty passes.

Example 4

The penetration performance of various coating compositions and coatingmethods were tested. In the following Tests A, B, and C, three differenttypes of needle coating compositions and application methods wereexamined. The penetration material for these tests was human cadavercarotid artery tissue.

TEST A

In Test A, commercially available Ethicon BV-1 surgical needles having a0.0105 inch diameter were tested. A coating was applied using theprocedures associated with the manufacture of this series. Inparticular, a silicone dip was prepared using a concentration of NuSil®Product No. MED4162. The needles were placed on a moving carrier stripand dipped a first time. The needles were then flash cured in a hot boxat approximately 190 degrees Celsius for twenty seconds. The needleswere dipped a second time and flash cured again at the same settings asabove. Finally, the needles were dipped a third time and then cured in aconvection oven for 8 to 16 hours at 190 degrees Celsius.

TEST B

In Test B, Ethicon tungsten-rhenium alloy needles having a 0.0105 inchdiameter were tested. The needles were prepared by applying theMomentive® SS4044P primer coat at room temperature. A base coatingcomposition was then applied over the primer using swirl coatingtechniques. The base coating composition was made by combining 27.58 wt.% of the Momentive®, vinyl siloxane polymer, product no. MSC2631, with72.25 wt. % of the HFE 72-DE solvent and agitated for about fiveminutes. Momentive®, catalyst in toluene, product no. SS8010, was thenadded to the mixture at 0.02 wt. %, and Momentive®, polymethyl hydrogensiloxane, product no. SS4300, was added at 0.14 wt. %. The base coatingwas applied to the surgical needles using the Asymtek C-341 ConformalCoater and the Asymtek SC-300 Swirl Applicator. The needles were thenheated to 300 degrees Celsius for thirty seconds in an infrared heater.

A top coating composition was then applied to the needles and was formedfrom 26 wt. % of the NuSil® MED4162 silicone product combined with 74wt. % of the HFE 72-DE solvent. The top coating composition was alsoapplied using swirl coating techniques with the Asymtek C-341 ConformalCoater and the Asymtek SC-300 Swirl Applicator.

The needles included in Test B were then batch cured at 80 degreesCelsius for three hours in a convection oven. The needles were tested bypassing each needle thirty times through the penetration membrane.

TEST C

In Test C, a competing brand of commercially available surgical needles(0.010 inch diameter), typically used in similar procedures, was testedout of the package. The needles were tested by passing each needlethirty times through the penetration membrane.

FIG. 9 is a graphical representation of the averaged results of Tests A,B, and C in direct comparison. The y-axis shows the penetration force ingrams needed to pass a needle through human cadaver tissue. The x-axisshows the number of passes. The triangular points represent the needleswith the conventional dip coating, as set forth in Test A above. Thecircular points represent the needles prepared according to the presentinvention as forth in Test B above. The diamond points represent thecompeting brand of needles as set forth in Test C above.

As shown, the commercially available Test A needles having a dip coatinginitially required an average penetration force of about 16 g. Theaverage penetration force for the Test A needles increased to about 18 gafter thirty passes. The Test B needles with the coating according tothe present invention performed with an initial average penetrationforce of about 13 g and maintained this penetration force after thirtypasses. The competing brand of needles performed with an initial averagepenetration force of about 15 g and resulted in an average penetrationforce of about 25 g after thirty passes. As can be seen, the needles inTest B required significantly less penetration force up to thirtypasses.

The use of two coatings as described above with respect to the presentinvention results in surgical needles that exhibit reduced tissuepenetration force compared with standard surgical needles after anequivalent number of passes through tissue. Thus, both the lubricity ofthe needle as well as the durability of the coating is improved. This isbelieved to result for a number of reasons. For example, application ofthe base and top coats using a swirl coating process provides an evendistribution of the coatings over the substrate. Furthermore, thecomposition of the coatings in combination with the methods ofapplication and curing can result in significantly decreased averageforce required to repeatedly pass the needle through tissue. The curingtime is also significantly decreased, resulting in more efficientmanufacturing processes.

Example 6

The penetration performance of a medical device coated with a single,homogeneous coating was tested in comparison with the performance of amedical device coated with both top and base coatings. In the followingTests A, B, C, and D, two different types of needle coating compositionsand application methods were examined. The needles were passed throughMonmouth rubber synthetic media.

TESTS A, B, and C

In Tests A, B, and C, ten commercially available Ethicon PS-2 surgicalneedles having a 0.024 inch diameter were tested. The ten test needlesin each test were coated with a single, homogeneous coating. In Test A,the single, homogeneous coating was composed of a “Component A” mixtureformed from 18.38 wt. % of the vinyl-functionalized organopolysiloxane,i.e., Momentive® Product Code No. MSC2631 silicone manufactured byMomentive® Performance Materials of Waterford, N.Y., 8.667 wt. % of thehydroxyl terminated polydimethylsiloxane, i.e., NuSil® TechnologiesSilicone Product No. MED4162 manufactured by NuSil® Technologies ofCarpentaria, Calif., 72.85 wt. % of the HFE solvent, 0.0165 wt. % of thecatalyst, and 0.0936 wt. % of the crosslinker. The Component A mixturewas equivalent to a 2:1 ratio of the base coating and top coatingsolutions and was mixed from master batches of the base and top coatingsolutions.

In Test B, the single, homogeneous coating was composed of a “ComponentB” mixture formed from 13.78 wt. % of the vinyl-functionalizedorganopolysiloxane, i.e., Momentive® Product Code No. MSC2631 siliconemanufactured by Momentive® Performance Materials of Waterford, N.Y.,13.00 wt. % of the hydroxyl terminated polydimethylsiloxane, i.e.,NuSil® Technologies Silicone Product No. MED4162 manufactured by NuSil®Technologies of Carpentaria, Calif., 73.13 wt. % of the HFE solvent,0.0124 wt. % of the catalyst, and 0.0702 wt. % of the crosslinker. TheComponent B mixture was equivalent to a 1:1 ratio of the base coatingand top coating solutions and was mixed from master batches of the baseand top coating solutions.

In Test C, the single, homogeneous coating was composed of a “ComponentC” mixture formed from 9.189 wt. % of the vinyl-functionalizedorganopolysiloxane, i.e., Momentive® Product Code No. MSC2631 siliconemanufactured by Momentive® Performance Materials of Waterford, N.Y.,17.33 wt. % of the hydroxyl terminated polydimethylsiloxane, i.e.,NuSil® Technologies Silicone Product No. MED4162 manufactured by NuSil®Technologies of Carpentaria, Calif., 73.42 wt. % of the HFE solvent,0.0083 wt. % of the catalyst, and 0.0468 wt. % of the crosslinker. TheComponent C mixture was equivalent to a 1:2 ratio of the base coatingand top coating solutions and was mixed from master batches of the baseand top coating solutions.

The ten test needles in each test were swirl coated with the single,homogeneous coating composition using a single pass spray using theSC-300 Swirl Coat™ Applicator and the Century® C-341 Conformal CoatingSystem available from Asymtek® of Carlsbad, Calif. with the followingparameters: 10 PSI fluid pressure, 50 PSI air assist, and a needle valvesetting of 8. The coated needles were then heated to approximately 200degrees Celsius in an infrared heater for about 20 seconds at ambientatmosphere.

As shown in Tables 7-9 below, the ten needles of each Tests A, B, and Cwere tested with thirty passes through the penetration membrane.

TABLE 7 Pass # → Penetration (g) Experiment Needle 1 2 3 4 5 6 7 8 9 1011 12 13 14 15 Test A 1 43 49 51 53 55 55 56 57 58 59 59 59 60 60 61 240 45 47 49 50 52 53 54 55 56 57 57 58 59 59 3 42 47 49 51 52 54 55 5557 58 59 59 60 60 61 4 42 46 48 51 52 54 56 57 58 59 60 61 61 62 63 5 4246 48 50 52 54 55 58 60 61 62 63 63 64 64 6 42 46 49 51 53 54 54 55 5758 58 60 60 60 61 7 43 48 51 53 56 58 59 60 62 62 63 63 64 64 64 8 40 4548 49 50 52 53 54 55 56 57 57 58 58 58 9 40 45 47 49 51 52 53 55 56 5658 58 59 59 60 10 39 42 45 47 48 49 50 51 52 53 54 54 55 56 57 Avg. 4146 48 50 52 53 54 56 57 58 59 59 60 60 61 St. Dev. 1.4 1.9 1.8 1.9 2.42.4 2.4 2.5 2.8 2.7 2.6 2.8 2.6 2.5 2.4 Pass # cont'd → Penetration (g)Experiment Needle 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Test A 161 61 61 61 61 62 62 61 61 62 63 63 63 63 63 cont'd 2 60 60 61 62 63 6363 64 64 64 64 65 65 66 66 3 62 62 63 64 64 65 65 65 65 65 66 66 65 6666 4 66 64 64 64 64 65 66 65 66 66 66 66 66 66 67 5 65 65 66 66 66 67 6767 68 68 69 69 69 69 69 6 62 62 63 63 63 63 64 65 65 65 66 66 66 67 68 765 63 64 64 65 66 66 65 66 66 66 66 66 67 66 8 59 59 59 59 59 60 60 6161 61 61 61 61 62 61 9 61 61 62 62 62 62 63 64 64 64 64 65 65 65 66 1057 57 58 58 59 59 60 61 60 61 61 62 62 62 62 Avg. 62 61 62 62 63 63 6464 64 64 65 65 65 65 65 St. Dev. 2.9 2.4 2.4 2.5 2.4 2.6 2.5 2.1 2.6 2.32.5 2.3 2.3 2.3 2.6

TABLE 8 Pass # → Penetration (g) Experiment Needle 1 2 3 4 5 6 7 8 9 1011 12 13 14 15 Test B 1 52 59 61 63 65 67 68 68 70 71 71 72 73 73 74 241 46 48 50 50 52 53 54 55 56 57 58 58 59 60 3 40 44 47 49 50 52 53 5455 56 57 58 58 59 60 4 41 45 47 49 50 52 53 54 55 56 56 57 57 58 59 5 3741 44 45 47 48 49 50 51 52 52 52 53 54 54 6 39 44 47 49 50 52 53 54 5556 57 58 58 59 60 7 45 49 51 52 54 54 55 56 56 57 57 58 59 59 59 8 39 4446 47 49 50 51 52 53 54 54 55 56 56 57 9 40 44 46 47 48 50 52 52 54 5455 56 57 57 58 10 40 44 46 48 49 50 51 52 53 54 55 56 56 56 57 Avg. 4146 48 50 51 53 54 55 56 57 57 58 59 59 60 St. Dev. 4.2 5.0 4.8 5.0 5.25.3 5.2 5.0 5.2 5.3 5.2 5.3 5.4 5.2 5.3 Pass # cont'd → Penetration (g)Experiment Needle 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Test B 174 74 75 76 75 76 77 77 78 78 78 79 79 79 80 cont'd 2 60 61 61 61 62 6364 65 66 66 67 67 67 67 67 3 60 60 61 62 62 64 63 63 64 64 64 64 64 6564 4 60 60 60 61 61 61 62 62 62 62 62 62 63 63 63 5 55 55 56 56 57 57 5758 58 58 59 58 58 59 59 6 60 61 62 62 62 62 63 63 64 64 65 65 65 65 65 760 60 60 60 60 61 61 62 62 62 62 63 62 63 63 8 57 57 57 58 58 58 58 5959 59 60 60 60 60 60 9 59 60 60 60 61 61 61 61 62 62 62 62 62 62 63 1058 58 58 59 59 60 60 60 60 60 60 61 61 61 61 Avg. 60 61 61 62 62 62 6363 64 64 64 64 64 64 65 St. Dev. 5.1 5.1 5.3 5.4 5.0 5.3 5.5 5.3 5.6 5.65.5 5.8 5.8 5.7 5.9

TABLE 9 Pass # → Penetration (g) Experiment Needle 1 2 3 4 5 6 7 8 9 1011 12 13 14 15 Test 1 41 45 48 49 51 53 54 56 57 57 58 59 60 61 62 C 241 46 49 51 53 55 56 58 60 60 61 62 63 63 64 3 42 46 49 51 52 53 54 5556 57 57 58 58 60 60 4 39 43 46 48 50 51 52 53 55 56 56 57 58 60 61 5 4047 51 53 54 56 57 58 59 60 60 62 62 62 63 6 39 43 46 48 50 52 54 55 5657 57 58 59 59 59 7 40 44 48 50 52 54 55 56 58 58 59 60 60 61 62 8 40 4548 50 52 54 56 58 59 60 61 62 63 63 64 9 40 46 48 50 52 53 55 55 57 5858 59 60 60 61 10 39 45 48 50 52 53 55 56 56 57 58 58 59 59 60 Avg. 4045 48 50 52 53 55 56 57 58 59 60 60 61 62 St. Dev. 1.0 1.3 1.4 1.5 1.21.4 1.4 1.6 1.6 1.5 1.7 1.9 1.9 1.5 1.7 Pass # cont'd Penetration (g)Experiment Needle 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Test C 162 63 63 64 63 64 64 65 66 66 66 66 66 66 66 cont'd 2 64 66 69 70 70 7071 71 71 71 71 71 71 72 72 3 60 61 60 61 61 61 63 62 63 63 63 64 64 6364 4 63 63 63 64 64 65 65 65 65 65 65 64 65 65 66 5 63 64 64 63 65 65 6566 67 67 67 67 67 67 67 6 60 60 60 61 61 62 62 62 62 65 66 67 68 68 68 763 63 63 64 64 64 64 65 65 65 66 66 66 67 66 8 64 66 66 66 66 66 66 6667 67 67 67 68 68 68 9 61 62 62 62 62 62 63 63 63 64 64 64 66 65 65 1060 61 62 63 62 63 64 64 64 65 65 65 65 65 66 Avg. 62 63 63 64 64 64 6565 65 66 66 66 67 67 67 St. Dev. 1.6 2.0 2.7 2.7 2.7 2.6 2.5 2.6 2.6 2.22.2 2.1 2.0 2.5 2.2

TEST D

In Test D, ten commercially available Ethicon PS-2 surgical needleshaving a 0.024 inch diameter were tested. The needles were prepared byapplying a base coating composition using the swirl coating techniquesand parameters described above in Tests A, B, and C. The base coatingcomposition was made by combining 27.58 wt. % of Momentive®, vinylfunctionalized base polymer, product no. MSC2631, with 72.25 wt. % ofthe HFE 72-DE solvent. Momentive® catalyst in toluene, product no.SS8010, was then added to the mixture at 0.02 wt. %, and Momentive®polymethyl hydrogen siloxane crosslinker, product no. SS4300 was addedat 0.14 wt. %. The base coating was applied to the surgical needlesusing the Asymtek C-341 Conformal Coater and the Asymtek SC-300 SwirlApplicator. The needles were then heated to 300 degrees Celsius forthirty seconds in an infrared heater.

A top coating composition was then applied to the needles and was formedfrom 26 wt. % of the NuSil® MED4162 silicone product combined with 74wt. % of the HFE 72-DE solvent. The top coating composition was alsoapplied using swirl coating techniques with the Asymtek C-341 ConformalCoater and the Asymtek SC-300 Swirl Applicator.

The needles included in Test D were then batch cured at 140 degreesCelsius for three hours in a convection oven. The needles were tested bypassing each needle thirty times through the penetration membrane. Theforce required to do so is set forth in Table 10.

TABLE 10 Pass # → Penetration (g) Experiment Needle 1 2 3 4 5 6 7 8 9 1011 12 13 14 15 Test D 1 46 50 51 53 54 55 55 56 57 58 58 58 58 58 58 248 52 56 56 58 60 61 62 62 63 64 64 64 64 65 3 47 50 52 53 54 56 56 5758 58 58 58 58 59 60 4 43 46 47 48 49 50 50 50 51 52 52 54 55 55 55 5 4548 49 50 50 52 52 53 53 54 54 55 55 55 55 6 47 49 50 52 52 53 54 54 5556 56 56 56 57 57 7 46 49 50 51 52 52 53 53 52 53 54 54 55 56 56 8 44 4548 48 49 50 50 50 50 51 51 52 53 53 54 9 45 48 48 51 52 53 54 54 55 5556 57 57 57 58 10 44 47 48 49 49 50 51 51 51 51 52 52 52 52 53 Avg. 4648 50 51 52 53 54 54 54 55 56 56 56 57 57 St. Dev. 1.6 2.1 2.6 2.5 2.93.2 3.3 3.7 3.8 3.8 3.9 3.6 3.3 3.4 3.5 Pass # cont'd → Penetration (g)Experiment Needle 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Test D 159 60 60 61 60 61 62 62 62 64 64 65 66 66 66 cont'd 2 66 66 67 67 67 6867 67 68 68 69 68 68 69 69 3 60 60 60 61 61 62 62 62 61 62 62 62 62 6263 4 55 56 56 56 57 57 58 58 58 58 58 59 59 59 59 5 56 56 58 58 59 59 6060 60 60 60 61 61 62 61 6 58 59 59 59 59 60 60 60 60 60 60 60 61 60 60 756 56 57 58 58 57 58 58 58 59 59 59 59 59 60 8 54 55 54 54 54 55 55 5556 56 56 56 56 57 57 9 58 58 59 59 59 59 60 60 62 60 60 61 61 62 62 1053 53 54 54 54 54 55 55 55 55 55 55 55 55 56 Avg. 58 58 58 59 59 59 6060 60 60 60 61 61 61 61 St. Dev. 3.7 3.6 3.7 3.8 3.7 4.0 3.6 3.6 3.7 3.84.0 3.9 4.0 4.1 3.9

FIG. 10 is a graphical representation of the averaged results of TestsA, B, C, and D in direct comparison. The y-axis shows the penetrationforce in grams needed to pass a needle through the penetration membrane.The x-axis shows the number of passes.

As can be seen, the needles that were coated with a single, homogeneouscoating had an initial penetration force of about 41 g in Tests A and Band about 40 g in Test C. The penetration force increased somewhat overthe thirty passes, and the needles required an average maximum force ofabout 65 g in Tests A and B and about 67 g in Test C after thirtypasses. In contrast, the needles that were coated with the two coats,i.e., the base coating and the top coating, had an initial penetrationforce of about 46 g. The average maximum penetration force after thirtypasses was about 61 g. As shown, the needles that were coated with asingle, homogeneous coat initially required about 5 g to 6 g less forceon average than the needles that were coated with two layers.

The use of a single, homogeneous coating as described above with respectto the present invention results in surgical needles that exhibitreduced initial tissue penetration force compared with both surgicalneedles having two coats and with standard surgical needles after anequivalent number of passes through tissue. Thus, both the lubricity ofthe needle as well as the durability of the coating is improved. This isbelieved to result for a number of reasons. For example, application ofthe single, homogeneous coating using a swirl coating process providesan even and thin distribution of the coating over the substrate.Furthermore, the composition of the coating in combination with themethods of application and curing can result in significantly decreasedaverage force required to repeatedly pass the needle through tissue. Thecuring time is also significantly decreased compared to the cure timerequired when two coatings, such as the top coating and the basecoating, are used, resulting in more efficient manufacturing processes.

One skilled in the art will appreciate further features and advantagesof the invention based on the above-described embodiments. Accordingly,the invention is not to be limited by what has been particularly shownand described, except as indicated by the appended claims. Allpublications and references cited herein are expressly incorporatedherein by reference in their entirety.

What is claimed is:
 1. A method for coating a medical device,comprising: spray coating a primer onto a refractory alloy surface of asurgical needle, the surgical needle having a tissue penetrating tip ata distal end thereof and a suture attachment portion at a proximal endthereof; and applying, as a liquid spray, a base coating to at least aportion of the primed surface of the surgical needle, the base coatingcomprising a vinyl functionalized organopolysiloxane, wherein the basecoating is applied as a single layer.
 2. The method of claim 1, furthercomprising curing the base coating.
 3. The method of claim 1, furthercomprising applying, as a liquid spray, a top coating over the basecoating, wherein the top coating comprises a polydimethylsiloxane. 4.The method of claim 3, further comprising curing the applied top coatingfor about 15 minutes to about 4 hours.
 5. The method of claim 1, whereinat least one of the spray coating of the primer or the application ofthe base coating comprises swirl coating.
 6. The method of claim 1,wherein the surgical needle is formed from a tungsten-rhenium alloy. 7.The method of claim 1, wherein the base coating further comprises asolvent having a boiling point less than about 43 degrees Celsius. 8.The method of claim 7, wherein the solvent is a hydrofluoroethersolvent.
 9. The method of claim 1, further comprising curing the basecoating for about 1 second to about 60 seconds.
 10. A surgical needle,comprising: an elongate body having a tissue penetrating tip at a distalend thereof and a suture attachment portion at a proximal end thereof,wherein the elongate body has a refractory alloy surface; a primercoating comprising a silicone disposed on the refractory alloy surface;and a base coating applied to at least a portion of the primer coating,the base coating comprising a vinyl functionalized organopolysiloxane.11. The surgical needle of claim 10, wherein the refractory alloy is atungsten-rhenium alloy.
 12. The surgical needle of claim 10, wherein theprimer coating comprises polyakylsiloxane and tetraethyl silicate. 13.The surgical needle of claim 10, wherein the primer coating iscovalently bonded to the surface.
 14. The surgical needle of claim 10,wherein the base coating is bonded with the primer coating.
 15. Thesurgical needle of claim 10, further comprising a top coating disposedon the base coating, wherein the top coating comprises apolydimethylsiloxane.
 16. The surgical needle of claim 15, wherein thebase coating is formed from a base coating composition comprising thevinyl functionalized organopolysiloxane and a hydrofluoroether solvent,and the top coating is formed from a top coating composition comprisingthe polydimethylsiloxane and a hydrofluoroether solvent.
 17. Thesurgical needle of claim 10, wherein the surgical needle is configuredto have a substantially constant tissue penetrating force after at leastthirty passes of the tissue-penetrating end of the elongate body throughtissue.